BACKGROUND: It is still under debate whether subjects with persistently elevated clinic blood pressure but normal ambulatory blood pressure, [white-coat hypertensives (WCH)] have a higher propensity for further development of ambulatory hypertension. METHODS: We prospectively evaluated for 3.5 years (from 26 up to 59 months) the transition of clinic and ambulatory blood pressure values in 36 untreated subjects (17-65 years) with WCH (clinic blood pressure > 140/90 and awake ambulatory blood pressure < 132/84 mmHg and without any other major cardiovascular risk factors) and of 52 clinic and ambulatory normotensive subjects (clinic blood pressure < 140/90 mmHg and awake blood pressure < 132/84 mmHg, 24-61 years). RESULTS: Average values of clinic blood pressure, 24 h blood pressure and awake blood pressure values did not differ from baseline to the end of the follow-up period in both populations. Development of ambulatory hypertension occurred in four out of 36 (11%) subjects with WCH and in three out of 52 (6%) normotensives if defined by awake blood pressure >/= 140/90 mmHg and in eight out of 36 (22%) subjects with WCH and in eight out of 52 (15%) normotensives if defined by awake blood pressure >/= 132/84 mmHg, respectively. Patients who reached ambulatory hypertension had baseline awake blood pressure values within the upper quintile of distribution of blood pressure in their respective group. CONCLUSION: After an average of 3.5 years of follow-up, a transition to ambulatory hypertension occurred in a similar way in normotensives and subjects with WCH without any other cardiovascular risk. A small propensity for the development of sustained hypertension may affect patients with higher initial ambulatory blood pressure values. Although a slow evolution towards sustained hypertension cannot be excluded in subjects with WCH, these findings suggest that this transition might be similar to that in normotensive subjects.